What term describes the function of digital signatures concerning the ownership of a private key?

The function of digital signatures in relation to the ownership of a private key is best described by the term nonrepudiation. Nonrepudiation provides assurance that a transaction or communication is authentic, meaning that the sender cannot deny having sent the message or signed the document. This is accomplished through the use of a digital signature, which is generated using the sender's private key.

When a digital signature is applied to a message or document, it ties the owner's identity to that signature, ensuring that only the owner of the associated private key could have created that specific signature. Thus, if a recipient verifies that the digital signature is valid and corresponds to the purported sender's public key, they can be confident that it was indeed the sender who signed it and cannot later claim otherwise.

In contrast, the other terms like authentication focus on verifying the identity of a user or system, integrity pertains to ensuring that data has not been altered in transit, and confidentiality refers to protecting data from unauthorized access. While these concepts are essential in the context of digital security, they do not specifically address the aspect of holding someone accountable for their actions, which is the essence of nonrepudiation.